When Ajay Ahir agreed to come to the United States, he had no idea the recruiter promising a high-wage welding job and legal residency in America was lying. He borrowed Rs 5 lakh ($7,633) to pay the recruiter's fees, told his wife to wait for him in India, and set off to make his fortune.

Almost nine years later, he has not returned.

When he arrived in New Orleans in January 2007, he was paid only half the $15 an hour he had been promised to work in shipyards devastated by Hurricane Katrina. And instead of a green card, his employer, Eagle Staffing of Louisiana LLC, got him a 10-month guest-worker visa for blue-collar labourers filling jobs that no American citizens want.

After that visa expired and Eagle went out of business, the US government recognised Ahir as a victim of human trafficking in July 2013, granting him a rare "T visa" that allows victims of forced labour to return home, collect family and re-settle in the United States.

But he still can't get home. His problem now is the Indian government.

Ahir's predicament illustrates how a US visa programme for trafficking victims has broken down in the aftermath of a diplomatic firestorm set off by the 2013 arrest of Indian diplomat Devyani Khobragade in New York that plunged the two countries into their fiercest dispute in years.

Indian government documents reviewed by Reuters show New Delhi has imposed restrictions over the past 16 months on Indian passports stamped with T visas, which give legal status in the US to trafficking victims if they agree to testify against those who smuggled them.

Between July 2014 and March 2015, at least 20 passports of Indians stamped with T visas were confiscated by authorities at Indian airports, preventing trafficking victims who returned home to collect their families from flying back to the United States, according to Jean Stockdale, a church worker who helps trafficking victims apply for the visas from her base in New Jersey.

That has now stopped. But since March, Indians who have received US T visas have faced new restrictions. T-visa holders face long delays in renewing passports at Indian consulates. They also must provide confidential information to the Indian government that they had previously submitted to the US authorities, including details about who had trafficked them, according to the documents, legal advocates and interviews with T visa holders.

Legal advocates for people such as Ahir say India's failure to recognise all T visas and attempt to seek confidential information on alleged traffickers raise the risk that victims or their families will face reprisals.

US officials say they are also concerned over what they see as India's reluctance to recognise a US congressionally-mandated visa for people the US government considers victims of human trafficking.

"We are deeply concerned by reports that some Indian nationals holding US T visas have experienced travel restrictions," the US State Department said in a response to questions from Reuters. "The current status of the policy is unclear, and we continue to ask the government of India at high levels in Washington and in New Delhi to fully repeal the policy."